<!DOCTYPE html>
<html lang="zh-CN">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    * {
      padding: 0;
      margin: 0;
    }

    div {
      height: 100vh;
    }

    #red {
      background-color: rgba(255, 0, 0, 0.2);
    }

    #green {
      background-color: rgba(0, 255, 0, 0.2);
    }

    #blue {
      background-color: rgba(0, 0, 255, 0.2);
    }
  </style>
</head>

<body>
  <div id="red"></div>
  <div id="green"></div>
  <div id="blue"></div>
</body>

</html>